Asymmetrical antenna with shielded feed line



Feb. 1942- H. J. R. VON BAEYER ET AL 9 I ASYMMETRICAL ANTENNA WITHSHIELDED FEED LINE Filed Oct. 17. 1940 Bxmentors lustrate modificationsthereof.

Patented Feb. 24, 1942 UNITED ASYMMETRICAL ANTENNA WITH SHIELDE FEEDLINE,

Hans Jakob Bitter von Baeyer and Hans Otto Roosenstein, Berlin, Germany,assignors to Telefunken Gesellschaft fiir Drahtlose Telegraphic in. b.IL, Berlin, Germany, a corporation of Germany I Application October '17,1940, Serial Nd asnssz i In Germany May 23, 1939 5 Claims (Cl. 25033);When feeding asymmetrical antennas such as,

for instance, M4 transmission radiators or receiving radiators fromshielded high frequency cables it is known that on the outside of thecab-1e covering so called cover waves appear causing disturbanceespecially in the radiation diagram and practically obviating again theby-pass lines of known type. in order to render the feeding symmetrical,theradiating part of the outer covering'must also be built as a dipoleuseful action of the cable shielding. In order to suppress thesecovering waves it is known to place at the end of the cable line currentresonant structures unilaterally tuned with the cable covering and inthe form of parallel rods, for

instance, which absorb the current coming from the interior of the cableso that this current is prevented from passing along the cable covering.In order to balance asymmetrical cable lines so-called blocking cupsalso have become known which comprise essentially a tubular conductorconnected unilaterally to the 'cable covering. 0n the open end of saidconductor thereappears a very high resistance (resonance resistance).

- In accordance with the present invention, such a blocking cup canserve for the suppression of the cable covering waves in that there issituated below the end of the cable covering, at a distance of a quarterwave or an odd multiple thereof, the open end of a quarter wave cupconnected at one side of the cable covering and so arranged that theline covering oscillates freely as a radiator. In this way the currentpassing out of the interiorof the cable on the inside of the outercovering is next absorbed by the outside of the covering and usefullyemployed for a defined radiation while being prevented from furtherpropagation along the cable covering.

The general idea of the present invention is.

illustrated in Figure 1, while Figures 2 and 3 il- In Figure 1 a coaxialline comprising an inner conductor J and an outer conductor A serves forfeeding a V4 radiator S. Below the end of the cable covering and at adistance of M4 there is arranged a blocking cup T with a sliding-bottomB by means of which the covering waves below the open end of the cupwill be completely suppressed in practice. The part of the coveringsituated above this openend, however, oscillates freely and completesthe M4 radiator 6 as can be seen from the dotted line indicated currentdistribution I so that said radiator forms a )\/2 dipole.

According to a further extension of the idea of the invention theantenna may consist also of a dipole line in which the currentsofundesirable phase are absorbed and rendered ineffective by line. Thisis shown in Figure 2 in which the actual antenna comprises two parts S1and S2 whose current distribution is indicated by line I. A by-pass lineis represented by the cup-shaped structure LA; In the case of thecurrent distribution shown in the drawing the organ LA is to form aninductive resistance. Exactly the same arrangement is placed also at theouter covering, whereby again aby-pass line LM is employed. The actualblocking cup for suppressing the covering waves is arranged below theradiating part and is designated by T.

ll igureli shows a mode of construction of the arrangement illustratedby the Figure 2. The by-pass lines, as well as the blocking cup, arehereby in the form of recesses in the antenna conductor and inv theouter covering and symmetrical to the axis so that smooth exteriorsurfaces are obtained.

Instead. of using a blocking cup, also one or several \/2 parallel rodsmay, for instance, be

employed.

We claim: 1. In association with a concentric cable line having an innerconductor and an outer casing conductor, an antenna including a pair ofcoaxial quarter wave radiators, one of said radiators being constitutedby the end portion of said outer casing and the other by an extension ofsaid inner conductor beyond the said outer casing and means forpreventing the flow of high frequency energy along the outside of saidcasing including an auxiliary shell surrounding said outer casing andhaving an end adjacent said antenna and a connection between saidauxiliary shell and said casing, said connection being spaced from theend of said shell f a distance equal to a quarter of the length of theoperating wave.

2. In association with a concentric cable line having an inner conductorand an outer casing conductor, an antenna including a pair of coaxialquarter wave radiators, one of said radiators being constituted by theend portion of said outer casing and the other by an extension of saidinner conductor beyond said outer casing, said antenna also includingcoaxial half wave radiators at opposite ends of said pair of quarterWave radiators, each of said half wave radiators comprising a shellconductor connected internally at substantially its midpoint to oppositeends of said pair of quarter waveradiators and means for preventing theflow of high frequency energy along the outside of said casing includingan auxiliary shell surrounding said casing and having an end adjacentsaid antenna and a connection between said auxiliary shell and saidcasing, said connection being spaced from the end of said shell adistance equal to a quarter of the length of the operating wave.

3. In association with a concentric cable line having an inner conductorand an outer casing conductor, an antenna including a pair of coaxialquarter Wave radiators, one of said radiators having an inner conductorand an outer casing conductor, an antenna including a pair of coaxialquarter wave radiators, one of said radiators being constituted by theend portion of said outer casing and the other by an'extension of saidinner conductor beyond said outer casing, said antenna also includingcoaxial half Wave radiators at opposite ends of said pair of quarterWave radiators, each of said half Wave radiators comprising a shellconductor connected internally at substantially its midpoint to oppositeends of said pair of quarter Wave radiators, the length of said internalconnections being variable.

5. In association with a concentric cable line having an inner conductorand an outer casing conductor, an antenna including a pair of coaxialquarter Wave radiators, one of said radiators being constituted by theend portion of said outer casing and the other by an extension of saidinner conductor beyond said outer casing, said antenna also includingcoaxial half wave radiators at opposite ends of said pair of quarterwave radiators, each of said half Wave radiators comprising a shellconductor connected internally at substantially its midpoint to oppositeends of said pair of quarter wave radiators, each of said half Waveradiators having a diameter substantially the same as that of theadjacent quarter wave radiator portions.

HANS JAKOB RITTER VON BAEYER. HANS OTTO ROOSENSTEIN.

